Furnace



Nov. 18, 1941. I LER- FURNACE Filed Nov. 16, 1939 4 Sheets-Sheet lINVENTOR Z2 1. Mueller I ORIVE Y Nov. 18, 1941.

M. MUELLER 2,263,098,

FURNACE Filed Nov; 16, 1939 4 Sheets-Sheet 2 BY g A TTOZLNEY M. L.MUELLER Nov. 18, 1941.

FURNACE Filed Nov. 16, 1939 4 Sheets-Street 5 INVENTOR J. Muzzle;

l I! I TORNEY 0 In- I Nov. 18, 1941. L. MUELLER FURNACE Filed Nov. 16,1939 4 Sheets-Sheet 4 [N VENTOR Mari walla/1 BY A NEY Patented Nov. 18,1941 UNITED STATES PATENT OFFICE FURNACE Moritz L. Mueller, Grosse'Pointe, Mieh., assignor to Borg-Warner Corporation, Chicago, 111., a.corporation of Illinois Application November 16, 1939, Serial No.304,677

4 Claims.

This invention relates generally to -furnaces and has particularreference to a furnace which is arranged to positively circulate andfilter the air being heated.

It is an object of this invention to provide a furnace in which thenovel arrangement of the parts of the furnace provide for an efficientand compactly arranged furnace so that the overall dimensions arerelatively small.

It is another object of this invention to provide a furnace which may beprefabricated in sections so that very little work is required in thefield to assemble the furnace.

It is another object of this. invention to provide heat exchangesurfaces within a furnace in such a manner as to make use of practicallyall the heat generated by the burner.

It is another object of this invention to provide a furnace in which thedraft within the combustion chamber is maintained at a relativelyconstant figure-by means of a suction blower in the exhaust passage tothe chimney.

Itis another object of this invention to provide a furnace in whichpower for the process of combustion and power for circulating theairbeing heated is provided by a single motor.

Other objects and advantages of this invention will be apparent from aconsideration of the fol- .lowing specification taken in conjunctionwith the accompanying drawings of which there are four (4) sheets and inwhich:

Fig. 1 represents a cutaway perspective view of the furnace embodying myinvention, some of the parts of which having been omitted for the sakeof clarity in the drawings;

' Fig. 2 represents a vertical section taken along the line 2-2 of Fig.1 and looking in the direction of the arrows;

Fig. 3 represents a partially broken away section taken generally alongthe line 33 of Fig. 1;

Fig. 4 is a perspective view of a partially assembled furnace embodyingmy invention;

Fig. 5 represents a section taken along the line 5-5 of Fig. 3 andshowing the type of joint used to connect the two sections of myfurnace;

Fig. 6 represents a perspective view, partially broken away, of the heatexchange surfaces and combustion chamber used in my furnace; and

Fig. '7 shows a circuit diagram of the wiring connection used inoperating my furnace.

Manufacturers have tried for some time to develop a furnace ofrelatively large heating capacity which may be more or less completelyassembled at the plant under expert supervision and sent out into thefield and installed in the users home with very little labor on the partof the installing agent. This not only reduces the amount of tools andparts which the agent must keep on hand, but also provides for moreperfect inspection of the assembly and insures better operation of thefurnace after it has been installed. To this end, I have designed afurnace which may be divided generally into three sections. Each sectionmay be individually assembled under expert direction at the factory andshipped to the agent to be installed in the user's home.

As is illustrated in Fig. 1, my furnace consists generally of an outercasing l0 having a return air opening l2, a'heated air discharge orplenum chamber l4, and enclosed within the casing a combustion chamber[6, a radiator l8 surrounding the combustion chamber, a circulatingblower 20, 'a draft inducing blower 22, fuel pump and motor assembly 24,filters 26 and various duct forming partitions which will be moreparticularly described later. Access to the interior of the furnace isobtained through a door 28 in the front of the casing.

As illustrated in Figs. 2, 3 and 4, the casing of my furnace consists ofpanels which may be made up as single stampings or sections havingflanges 30 for bolting the various sections together. I have shown thesections of the casing to be made as two parts 32 and 34 each of whichincludes a side, half of the back and portions of the top and front ofthe casing. Each section is further divided along a horizontal planeapproximately in the middle of the fur-' 40 which defines a plenumchamber between itself and the partition 38, and defines a combustionand heating compartment between itself and the rear .wall of the casing.The partitions 3B and 40 are out near their midsections along a verticalline and each half is joined to its respective half of the outer casing.The sections of the partitions are then joinedby means of the jointillustrated in Fig. 5 which consists of, a return flange 42 on each partof the partition and a drive cleat 44 adapted to be driven over eachofthe return flanges. 4| indicates a cleanout port and 43 indicates aport for installing a thermostatic limit switch.

The casing is further divided from the top to the bottom by an arcuatepanel 46 which defines, between itself and the top of the casing, an airintake and filter chamber. The panel 46 is attached, as by welding, toone side of the casing at 48 and curved upwardly over and down theopposite side of the casing at 58 to form a duct-between itself and thecasing leading to the air circulating blower 20. The panel extends fromthe rear wall of the casing to the partition 48. As in the case of thepartition panels 38 and 40, the panel 46 is divided near its midsectionso that each half may be assembled with its respective part of thecasing proper. The two sections of this air duct partition may befastened to the rear wall of the casing and to thepartition 40 by meansof a flange 52 along its edges welded to the connecting part.

Near the lower portion of the casing proper, I have provided ahorizontal partition panel 56 which formsin conjunction with the airduct partition 46 and the vertical partition 40, a heat exchange chamberadapted to enclose the combustion chamber I6 and radiator I8. The panel56 has an opening 58 for receiving the discharge from the circulatingblower 28. As in the case of the other partition panels, the panel 56 isdivided into two sections for assembly with each section of the outercasing.

The forward partition 38 does not extend as far down the casing as doesthe partition 40 and the lower end of the space between the partitionsis closed off from the machine space within the casing by means of ahorizontal panel 68 which is also divided along the middle portion. Thepanel 68 may be formed by bending over the bottom portion of the panel38. When the panel 68 is sealed to the partition 48, it forms, inconjunction with that panel and partition 38, a plenum chamber extendingupwardly to the opening l4 which is then attached to the heatdistributing system in the house.

The partition panel 40 has a circular opening 62 out near its midsectionwhich is of such a size as to register with a flange on the radiatorwhich will be described later. The partition 38 has a somewhat smallercircular opening 64 which is concentric with the opening 62 and arrangedto register with the end of the combustion chamber as will be describedlater. The lower portion of the partition 40 has a small circularopening 66 cut in it immediately below the opening 62. This opening 66is arranged to register with the exhaust connection from the radiator aswill be more particularly described later. The middle of the panel 48may be sup ported from below by a panel 68 which fits around the opening66 and extends to the floor underneath the casing. .The panel 68 servesto reenforce the various partitions where they are fastened in thecenter of the casing since these partitions support the combustionchamber and radiator.

The heat exchan e surfaces, or radiator, and combustion chamber are moreclearly illustrated in Fig. 6 and consist of a circular drum 18 formingthe combustion chamber and having a flange 12 on its forward end. Therear end of the cylinder 10 is closed by a panel I4. Around the cylinder10 is arran ed an inner cylinder 16 and an outer cylinder 18 which areconnected and closed at each end by rings or plates 80 and 82. It shouldbe noted that the inner cylinder 16 is slightly longer than the outercylinder I8, thus forming a flange 84 at the forward end of theradiator. The two cylinders I6 and 18 thus form an annular passage whichis divided into a spiral passage by means of a spiral fin 86. This fin86 is formed of two angle members 88 and 90, one of which is welded tothe outer cylinder and one of which is welded to the inner cylinder inconfronting relationship with the first angular member. This spiral workconstruction is more particularly described and claimed in my U. S.Letters Patent for Air conditioning apparatus," No. 2,172,399, datedSeptember 12, 1939.

The combustion cylinder I0 has an opening 92 at the top and towards therear end of the cylinder. This opening 92 is connected by means of ashort section of pipe 94 with a corresponding opening 96 in the innercylinder I6 of the radiator. This passage allows the hot gases from thecombustion chamber to escape to the spiral passage of the radiator. Thepipe 94 also serves to support the radiator with respect to the rear endof the combustion chamber cylinder. The forward end of the radiator isheld in position relative to the combustion chamber by means of thestruts 85.

The forward end of the combustion chamber cylinder may be lined with aheat resisting material, such as fire brick, to prevent the burning ofthe metal at a point adjacent the end where the flame is propagated. Ihave shown this fire brick to consist of a circular lining 98, an enddisc I00 with a hole $02 in the center thereof, and a baiile I84 towardthe rear end of the flame retaining section of the combustion chamber.

It is to be noted that the combustion chamber cylinder I8 isconsiderably smaller than the inner cylinder I6 of the radiator, thus,there is provided an annular space between the radiator and thecombustion chamber through which air is adapted to pass into the plenumchamber. The flange 84, on the radiator registers with the opening 62-in the partition panel 48 and may be fastened thereto as by bolting orwelding. The opening 64 in the partition 38 registers with the flange 12on the forward end of the combustion chamber, and these parts may bejoined as by bolting or welding. The forward end of the combustionchamber and radiator assembly is thus supported upon the partitionpanels 38 and 40. The rear end of the combustion chamber may be furthersupported from the casing by means of a pipe I04 bolted or fastened tothe rear end of the combustion chamber and passed through the casing asat I06. The circular plate I08 is positioned directly behind thecombustion chamber to shield the outside wall of the casing from heatradiated from th combustion chamber. The plate may be held in spacedrelation with the casing by means of a series of clips IIll At the frontof the radiator, and at the bottom thereof, I have provided an opening II2 to which is connected a short pipe section H4 which projects throughthe hole 66 in the partition 48 and forms an exhaust opening for theradiator.

After the fire brick 88, I00 and I84 has been inserted into thecombustion chamber, the front plate H3 is then bolted over the front ofthe combustion chamber. Plate II3 has a thick ened portion or bossformed in the center thereof as indicated at H5. This boss 5 forms aburner unit having an inwardly conical bore I I6 and radially arrangedholes II8 extending into a central bore I28 which communicates axiallywith the hole I02 in the insulating material or fire brick I00. A burnernozzle I22 is positioned within the conical opening H6 as are twoignition electrodes I24, for igniting the mixture of oil and air passingthrough the opening.

burner to cease.

@ aaoaoss The air for heating the house is circulated through the houseby means of the blower 28 which consists of a wheel or fan I80positioned within a hood I02 having the intake opening I34 and adischarge opening 58 opening into the space around the radiator. The fanis provided with a pulley wheel I88 for rotating .the fan wheel by meansof a belt drive from the motor.

with a pulley I48 which is adapted to. drive the belt for driving theblower pulley I38. Also pipe I58 to the chimney. The base I42 hasattached thereto a crossbar member I80 for fastening the machine supportto the blower and to the supporting panel 88 thus insuring that theparts will be in proper alignment.

The controls and wiring for operating the furmice, as viewed in Fig. 2,consist of a terminal box I84, a thermostatic switch I88, providedsupported in the top of the casing by means of angle members 21 fastenedalong the wall of the J I The conditioning of the air within the furnaceis provided by means of the filters 28 which are casing and along thepartition 40 as well as across the center of the air intake chamber. Theair may be humidified by means of a body of water positionedinthe-panl80 at the bottom of the plenum chamber. The water supply may be kept ata constantlevel by means of afloat valve I82 connected to the pan I80 bya pipe Ill and to which a supply from the water system of the house isconnected. In case the filters 28 should become clogged, I have provideda by-pass damper I84 for the purpose of allowing air to escape past theclogged filters. In this manner there is no danger of there being a lackof air passing over the radiator and combustion chame her, and, thus,overheating is prevented. The

with a heat responsive element I88 within the plenum chamber,atransformer I10 for supplying current to the ignition electrodes I24and a protecto relay switch I12 having a thermostaticelement I14 withinthe pipe I58 and subject to the temperature of the exhaust gases. Adiagram of a possible wiring circuit is illustrated in Fig. '1 andoperates as follows: Current is supplied to the terminal box I84 bymeans of the power circuit from the house I15. From the terminal box thecircuit extends through the limit switch I88 to the transformer I10which provides currentto the electrodes I24. After passing thetransformer I10, the current is supplied to the protecto relay switchI12 which is a manual control for turning the circuit on or off and alsoincludes a delayed action circuit controlled by the thermostatic deviceI14. When the switch I12 is turned on, and after a definite time, if thetemperature-around the thermostatic device I14 has not risen to apredetermined figure due to the passage of burning gases therearound,the thermostatic switch I14 will reopen the motor circuit thus'causlngthe how of air and oil to the This is a safety feature in that apersoncan not turn on the furnace and go away and leave it running withoutflames starting. The furnace can not be filled with 9. dangerous mixtureof oil and air which might later explode. The limit switch I88 operatesto shut off the motor and furnace operation should the temperature inthe chamber rise too high as would be the case if the fan belt drivingthe circulating fan 20 were to break. It should be obvious that thecontrols for the furnace may be rearranged to suit most any operatingcondition and may include a thermostat in the space being heated.

damper I84 is so designed that on an increase in pressure the damperbecomes unbalanced and swings to a permanently open'position indicatingthat the filters are clogged and should be changed.

The passage through the furnace of air being heated is indicated by thefull-lined arrows and is as follows: Through the opening I2 in the topof the casing through the filters or through the by-pass damper down theside of the casing to the intake of the blower 20, then the air isforced upward inside of the-partition 48 and around the outside of theradiator. After passing around the radiator, the air passes back andaround the rear end of the radiator and into the annular passage betweenthe radiator and the combustion chamber. The air is forced through thisannular passage over the humidifying pan I80 and out through the plenumchamber past the limit switch control I88.

The path .of the products of combustion is indicated by the broken linearrows and is as fol- J lows: The air is drawn in through the conicalburner opening H8 and the radial openings II8 from the inside of thecasing due to the suction created by the exhaust blower 22. In theburner head the. air is mixed with oil from the nozzle I22 and isignited by the spark from the igniters I24. The resulting flame islargely confined to the space within the combustion chamber which islined with fire bricks. From there the hot gases pass into the rear endof the combustion chamber. out through the stack 84 in the top of thecombustion chamber in the radiator between the two outer cylinders. Inthe radiator the gases spiral around and towards the front where theypass out the opening I I2 through the pipe I58 past the thermostaticcontrol I14 for the protecto relay, then through the pipe I54 to theduct I52 which forms the intake for the blower 22. After passing throughthe blower the products of combustion are blown out the pipe I58 and upthe chimney.

It will be noted that with this arrangement I have provided that theflow of air being heated and the flow of the hot gases are reversed overthe heating surfaces so that the difference in temperature of the twopaths of gases is at a maximum at all time; thus, the air to be heated,which is coldest when it enters the furnace, is first brought in contactwith the circular panel 48 which will be heated to some extent byradiation from the radiator. After the air has picked up some heat fromthis panel, it is brought into contact with the hotter surfaces of.theradiator and, when the air has picked up heat from the radiator andhas risen to higher temperatures, it is conducted over the extremely hotsurfaces of the combustion chamber within the radiator. Since the amountof heat which a fluid will pick up in passing over a heated surfacedepends upon the difference in temperature between the fluid and thatsurface, it is evident that I have provided for amaximum amount of heattransfer between the air being heated and the products of combustion.

Since the draft for drawing air into the combustion chamber anddisposing of the products of combustion is maintained by the blower I50,

the furnace may be operated with practically any type of chimney.Further, the furnace may be tested and the controls adjusted at thefactory by experts without having to know the type and eiiiciency of thestack to which the furnace is to be attached. This insures efficientoperation' of the furnace regardless of the skill of the dealer whoinstalls it.

While I have described my invention in some detail, I intend thisdescription to be an example only and not limiting upon my inventionwhich is defined in the following claims.

I claim:

1. In a warm air furnace adapted to be erected in a confined area, asubstantially cylindrical combustion chamber, an annular elongatedradiator, said radiator being disposed about the outer wall of saidcombustion chamber in spaced apart relationship thereto and forming withsaid combustion chamber a unit assembly, an outer furnace casing dividedinto two parts separable at a vertical plane substantially bisecting thecasing longitudinally, and partial partition and supporting wallscarried by each of said casing parts arranged so that the said walls ofone said part cooperate with the said walls of the other said part tosupport said unit assembly substantially centrally within said casingand to provide air conducting passageways through the casing inimmediate contact with the exposed walls of the combustion chamber andradiator of said unit assembly.

2. In a warm air furnace as-defined in claim 1, the disposition of thesaid combustion chainber and radiator unit assembly being such that itscentral axis is in a horizontal plane extending longitudinally of saidcasing and vanes within said radiator directing the flow of hot gasesand products of combustion in a helical path during its passagelongitudinally through the radiator.

3. In a hot air heating assembly including a housing having a cold airinlet and a hot air outlet, means in said housing defining a path offlow for air from said inlet to said outlet comprising a generallycentrally positioned elongated drum-like stove, a hollow wall tubularradiator embracing said stove in spaced generally concentric relationthereto forming an air heating space therebetween, oil burning meanslocated in a first end portion of said stove, conduit means placing theother end of said stove in communication with the adjacent end of saidhollow radiator, flue defining means communicating with said radiatoradjacent said oil burn; ing means for removing combustion gases, meansincluding a blower for delivering substantially all of said cold airfrom said inlet first against the outside of said radiator, thencedelivering all of said air around the end of said radiator remote fromsaid oil burning means, then between said radiator and said stove, andconduit means adjacent said oil burning means for directing all of saidhot air from between said radiator and said stove to said hot airoutlet.

4. In a furnace including a surrounding housing provided with a cold airinlet and a hot air outlet, a stove and radiator arrangement within saidhousing defining an air heating space therebetween wherein the rate ofheat transfer from said stove and radiator to said air is made to besubstantially the same along the axial extent of said heating space,said arrangement comprising a central horizontally elongated drum-likestove, a hollow walled tubular radiator embracing said stove and spacedin generally concentric relation thereto, oil burning means located inone end of said drum-like stove, conduit means placing the other end ofsaid stove in communication with the juxtaposed end of said hollowradiator, flue defining means communicating with said radiator at theother end thereof adjacent said oil burning means for removingcoinbustion gases, means shutting off the entry of air between saidradiator and said stove adjacent said oil burning means, the spacebetween said stove and said radiators adjacent the other end thereofbeing open for the entry of air thereto, means including a blower fordelivering cold air from said inlet first against the outside of saidradiator thence around the open end of said radiator remote from saidoil burning means and then between said radiator and said stove, andconduit means adjacent the other end of said space juxtaposed to saidoil burning means for directing hot air from between said radiator andsaid stove to said hot air outlet.

MORITZ L. MUELLER.

